So far the handbrake is better than nothing, but there are some big areas of improvement. 

First, the return action isn't that great. There is basically no damping besides a small piece of foam, and if I pull and release the lever without being gentle it tends to shake and rattle the whole assembly apart. The spring I used initially was too long and made alot of noise. I bought some 15mmx40mm springs from Amazon for my G29 quick-ish release sequential shifter mod and they fit perfectly in the handbrake. I am looking at some 4 inch gas struts typically used for cabinets to provide damping, as I read RC shocks don't provide much damping force. 

Second, there was some weird issue with EA WRC, opentrack set to vjoy emulation, and the arduino serial port. It would basically break all three things at once, and I don't really know if anyone else would be experiencing the same thing. I redid the electronics a little nicer on some perfboard and added a reset switch as a bandaid solution for now. I found I never soldered the SCA pin on the magnetometer so I hope that helps fix things. 

Last, the constraint of using only ender 3 hardware makes space an issue. There is a lot of rubbing and squeaking going on. Hopefully I can find some cheap 4mm ID aluminum tube to make better spacers. 

The magnetometer works surprisingly well, I just need to tweak the signal filtering to be a little more responsive.